Abstract:

The evolution types of swamp muck milieus (ETSMM) of Jurassic basins in the Northwest of China were analyzed and investigated by the methods of coal geology.ETSMM'S basins were divided into three types: 1.lack of formations of lake facies in the coal-bearing basins; 2.without lake facies formation in the overlying measures on the Jurassic coal-bearing formations; 3.three evolution type of swamp muck milieus with cyclic sequences of lake-level change (eustasy).The organic maturity and compositions of macerals were investigated.Especially,the organic constitutions of macerals in the second and the third ETSMM's basins were contrasted and studied.It is suggested that coal-formed oil field would be formed in the basins developed the cyclic sequences of lake-level changes (eustasy),i.e.in the third ETSMM's basins.It is impossible that coal-formed oilfields can be found in the first and the second ETSMM's basins with the lower organic maturity (R₀<0.7%).

Key words: macerals, source rock maturity, coal-formed oil, evolution types of swamp, muck milieus, cyclic sequences of lake (sea)-level changes

摘要：

运用煤田地质学方法分析、研究了西北侏罗系盆地的煤沼沉积环境演化类型(以下简称煤沼演化类型),划分出:①没有发育湖相建造;②含煤建造上覆缺失湖相建造;③具有完整湖平面变化旋四层序的三种煤沼演化类型;研究了西北侏罗系含煤盆地,尤其是第二和第三煤沼演化类型的煤显微组分组成和烃源岩的成熟度特征.根据西北侏罗系含煤盆地煤成油田形成和分布规律,依据煤沼演化类型、盆地沉积构造背景、有机岩组成特征等条件,提出了天山及其以北和塔里木周缘和祁连山两侧山前的前陆盆地等同沉积构造活动性较强的盆地是西北侏罗系煤成油勘探的有利区域,发育第一和第二煤沼演化类型的盆地及其伊犁和三塘湖盆地没有找到煤成油田的可能的看法.

关键词: 煤显微组分, 成熟度, 煤成油, 煤沼演化类型, 湖平面变化旋回层